1. Technical Field
The present invention relates to piezoelectric elements, liquid ejecting heads, liquid ejecting apparatuses, and methods for the manufacture thereof.
2. Related Art
Piezoelectric elements and ink jet recording heads are manufactured by thin film technology in order to reduce the thickness of the piezoelectric elements and achieve high density and high-speed drive. For example, JP-A-2009-172878 discloses an ink jet recording head producible by thin film technology.
The ink jet recording head disclosed in JP-A-2009-172878 has a piezoelectric element in which lower electrodes provided on a vibration plate are covered with respective piezoelectric layers, and an upper electrode is formed so as to continuously cover a plurality of the piezoelectric layers. According to this piezoelectric element, the upper electrode reduces the influences of, for example, water in the air on the piezoelectric layers.
When a piezoelectric element having this structure is energized, an electric field tends to be concentrated in a region where a first electrode protrudes from a vibration plate toward a piezoelectric layer (for example, around the corner of the lower electrode), possibly resulting in a crack in, for example, the piezoelectric layer. There has thus been a need for a piezoelectric element which has a reduced concentration of an electric field in a piezoelectric layer during energization.